The present invention relates to an image-taking apparatus which adjusts focus of an image-taking optical system by using an image signal provided through photoelectrical conversion of an object image formed by the image-taking optical system and which allows recording of a still image during recording of a moving image.
Japanese Patent Laid-Open No. 2000-224458 has proposed a method of performing auto-focus (AF) operation quickly in still-image recording in an image-taking apparatus which allows moving-image recording and still-image recording. In the method, focus adjustment is performed continuously during moving-image recording, and to activate still-image recording during the moving-image recording, the focus adjustment continuously performed until that point is stopped.
Japanese Patent Laid-Open No. 2003-348426 has proposed a method of performing auto-focus operation quickly in still-image recording in an image-taking apparatus for still-image recording. The method involves a determination of the state of continuous AF processing before an instruction to start AF for still-image recording (detection of an S1 signal) during taking of a through image, and setting of a range and a direction of search for an in-focus position after the instruction to start AF for still-image recording depending on the determination result. Specifically, when the state of continuous AF processing immediately before the detection of the S1 signal is in the course of fine adjustment, only a region near the current position of a focus lens is searched for focusing.
When the focus lens is being driven toward a detected in-focus position, only a region near the detected in-focus position is searched for focusing. When the in-focus position is being searched for, the focus lens is driven for searching in the current driving direction from the current position to achieve focusing. In other cases, the entire region is searched for focusing.
In the method proposed in Japanese Patent Laid-Open 2000-224458, however, the continuous focus adjustment operation performed until the start of still-image recording is stopped at that point. If an in-focus state has not been achieved by the time the still-image recording is started, a focused still image cannot be recorded. The still-image recording may require a larger number of image pixels to be recorded than in the moving-image recording, and in this case, if the focus adjustment operation is stopped at the time of start of still-image recording, the still image may not be sufficiently focused even when an adequate in-focus state is achieved for a moving image.
On the other hand, in the method proposed in Japanese Patent Laid-Open No. 2003-348426, the AF processing state before the instruction to start AF for still-image recording is determined to set the AF operation after the instruction. If this is used in an image-taking apparatus which records a still image during moving-image recording, a focus lens is moved largely before the start of still-image recording to cause a great change of the focus state, resulting in the problem of recording of an unnatural moving image.